Grading and rejecting device



June 17, 1958 v c HALL GRADING AND REJECTING DEVICE Filed Nov. 2. 1954INVENTOR VICTOR C. HALL EM 80 mg Md, F044 4 ATTORNEYS United StatesPatent GRADING AND REJECTING DEVICE Victor C. Hall, Media, Pa.,assignor, by mesne assignments, to F. I. Stokes Corporation,Philadelphia, Pa., :1 company of Pennsylvania Application November 2,1954, Serial No. 466,378

4 Claims. (Cl. 241-79) This invention relates to the grading of smallsolid objects such as medicinal tablets to determine those that arebelow acceptable standards and to separate and remove them from theacceptable tablets. For convenience, the invention will be described inconnection with medicinal tablets of the type formed of compressedgranular material. The invention provides a yielda'ble, preferablyresilient, roller under which the tablets pass while supported on a hardbase, and means for adjusting the pressure which the roller exerts onthe tablets so that acceptable tablets pass uninjured while unacceptabletablets, such as those formed of an insuflicient amount of material, orwhich are physically miss'haped or otherwise defective, are crushed andin that form are separable from the other tablets.

The device of the invention is advantageously suitable for use incombination with automatic tablet forming machines of the type whichform the tablets by compression in dies and which also compress coatingsof granular material over previously formed core tablets. The inventionsolves an especially difficult problem in the grading of medicinaltablets having core tablets covered with coatings. Such coatings areusually formed by depositing the core tablet in a die over granularmaterial, then applying granular material over the core tablet, andcompressing the coating in the die between punches. The operation mayoccasionally fail to deposit a core tablet in one of the dies with theresult that a tablet will be formed only of coating material, or thetablet may result from the coating of an imperfect core tablet. Suchimperfect tablets have a difierent structure, hardness, and strengththan perfect tablets, and the roller is adjusted to crush them whilepermitting the perfect tablets to pass uninjured.

In a preferred embodiment and combination, the roller is formed ofrelatively resilient rubber and is mounted over a firm base on which thetablets travel and against which they are pressed by the roller. In onecommon tablet forming and coating apparatus, the tablets are removedfrom the dies and travel on a rotating bed over which the roller ismounted. The roller is adjustably mounted to vary the pressure on thetablets and is also preferably provided with means to rotate it,preferably at about the peripheral speed of the tablets traveling on therotating bed.

These and other objects of the invention will be better understood afterconsidering the following discussion taken in conjunction with theaccompanying drawings, in which:

Fig. 1 is a side elevation of a tablet grading device of the inventionillustrated in combination with parts of a rotary tablet forming andcoating machine, and

Fig. 2 is a plan view of the apparatus illustrated in Fig. 1.

The drawings illustrate only fragmentary portions of the well known andwidely used Stokes type tablet forming machine, modified to compressgranular coatings on core tablets, having a rotary die bed 1 comprisinga plu- 2,839,252 Patented June 17, 1958 rality of tablet forming dies 2in which the tablets are coated and when finished are pushed out of thedie to the level of the die bed on which they continue to rotate. Thebattle 3 is provided to deflect the coated tablets T away from the diesand to carry them under the roller 4 of the invention.

This roller 4 is formed of yieldable but relatively firm rubber and ismounted on a bearing sleeve 5, which is freely rotatable on the shaft 6and held in position by the nut 7. As illustrated in the drawings, theshaft is adjustably but securely mounted on the upright bracket 8 whichis rigidly attached to the stationary frame 9 of the tablet formingmachine. The bracket 8 has an upright slot 10 in which the shaft 6 isadjustable in an up ward and downward direction to vary the spacebetween the roller 4 and the die bed. The shaft can be secured in thedesired position by tightening the nut 11 against the collar 12 which isfixed to the shaft 6.

The roller '4 comprises a relatively large diameter drive wheel portion13 which makes bearing contact with the rotary bed 1 to drive theroller, and an integral smaller diameter portion 14 which is the partunder which the tablets must pass after being removed from the dies. Bysuitably adjusting the position of the shaft 6, varying de grees ofpressure may be applied by the roller portion 14- to the tablets.

With particular reference to Fig. 2, the finished coated tablets whichare pushed out of the dies contact the stationary battle 3 and aredeflected towards the central portion of the rotary die bed 1 anddirected to pass under the roller 4. If the tablets are properly formedas previously described, they pass under the roller without 1njury. Ifthey are not suitably formed, they are crushed or shattered by theroller. After the tablets pass under the roller, they engage thestationary bafiie plate 15 and are deflected from the rotary die bedfrom which they fall onto the angularly disposed screen 16. The brokenor crushed tablets fall through the screen into the receptacle 17. Theuninjured and acceptable tablets continue and fall into the receptacle18.

While the invention has been described in connection with a rotating diebed on which the tablets travel, it is to be understood that the tabletsmay be fed under the roller by any suitable means. The roller may bemechanically driven to rotate over a stationary base, or one moved in adifferent manner, such as a conveyor belt.

While the grading device of the invention can be used advantageously ingrading a variety of solid objects, prefera'bly formed of granularmaterials that are susceptible to crushing with the yieldable rubberroller, it is especially effective for use in connection with thegrading of medicinal tablets which have an inner core tablet coated witha granular material formed by compression in the type of apparatusillustrated. Such tablets are difiicult to grade, and the device of theinvention provides an effective means of detecting and removing tabletswhich are defective for various reasons.

I claim:

1. An improved device for grading small hard objects to separateimperfect objects which are structurally weak, have low density or areoversized, which device comprises a roller of resilient material, meansfor mounting said roller in spaced position above a hard base on whichthe objects travel in passing under the roller, said roller beingadjustable to provide the required pressure on the objects and saidresilient material being such that said imperfect objects are crushedwhile the remaining objects are not injured, and means for separatingthe remaining objects from the crushed objects.

2. An improved grading device according to claim 1 which comprises meansfor driving the roller at substantially the speed of travel of theobjects.

objects. 4. An improved, device for grading small hard objects toseparate imperfect objects which are structurally weak, have low densityor are oversized, which device comprises a roller-having one part ofrelatively large diame- 10 ter and having another part of smallerdiameter constructed'of resilient material, a hard base, said roller'being adjustable and, positioned above said base with said one partofsaid roller engaging said base and with said other partof said" rollerpas-sing above said base, means for moving said base relative to saidroller whereby the engagement of said one part of said roller with saidbase causes said roller to turn andwhereby said objects positioned onsaid'base are passed beneath said-other part of said roller and incontact with said roller, said imperfect objects thereby being crushedwhil'e' said remaining ob jects are not injured, and'rneans forseparating said crushed objects from said remaining whole objects.

References Cited in the file of this patent UNITED STATES PATENTS454,780 Thompson June 2-3; 189i 1,220,801 Varga Mar. 27, 1917. 1,515,654Burner Nov. 18, 1924 2,155,378 Albertali Apr, 25,, 1939 2,306,427Christian Dec. 29, 1942 FOREIGN PATENTS 805,542 France Aug. 22, 1936

